delete.php

<?php
/*
    Copyright (c) 2011 David Wolff

    Permission is hereby granted, free of charge, to any person obtaining a copy of 
    this software and associated documentation files (the "Software"), to deal in 
    the Software without restriction, including without limitation the rights to 
    use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies 
    of the Software, and to permit persons to whom the Software is furnished to do 
    so, subject to the following conditions:

    The above copyright notice and this permission notice shall be included in all 
    copies or substantial portions of the Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 
    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 
    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE 
    SOFTWARE.
 */

require 'includes/soss_common.php';
require 'soss_db.php';
require 'soss_request.php';
require 'soss_json.php';

// All delete actions require faculty auth
$auth = $_SESSION['auth'];
if( empty($auth) or $auth < AUTH_FACULTY ) {
	soss_send_json_response(SOSS_RESPONSE_PERMISSION_DENIED, "Access Denied.");
}

$target = soss_get_request('t');

if( $target == "assignment" ) {
	delete_assignment();
} elseif( $target == "class" ) {
	delete_class();
} elseif( $target == "student" ) {
	delete_student();
} else {
	soss_send_json_response(SOSS_RESPONSE_ERROR,"Unrecognized query.");
}

function delete_assignment() {
	try {
		$db = SOSS_DB::getInstance();
		
		$assign = soss_get_request('name');
		
		$sql = "DELETE FROM %s WHERE student_class_id=%s ";
		$sql .= "AND assignment_class_id=%s AND assignment_name='%s'";
		$sql = sprintf( $sql,
			SOSS_DB::$FILES_TABLE,
			$db->dbclean($_SESSION['classid']),
			$db->dbclean($_SESSION['classid']),
			$db->dbclean($assign) );
		$result = $db->query($sql);
		$files = mysql_affected_rows();
		
		$sql = "DELETE FROM %s WHERE class_id=%s ";
		$sql .= " AND name='%s'";
		$sql = sprintf( $sql,
			SOSS_DB::$ASSIGNMENTS_TABLE,
			$db->dbclean($_SESSION['classid']),
			$db->dbclean($assign) );
		$result = $db->query($sql);
		$assignments = mysql_affected_rows();
		
		$message = "Deleted $assignments assignment and $files file entries.";
		$message .= "<br />It is now safe to manually delete all files in the repository";
		$message .= " that are associated with assignment \"{$assign}\".";
		
		soss_send_json_response(SOSS_RESPONSE_SUCCESS, $message);
		
	} catch( SOSS_DB_Exception $e ) {
		soss_send_json_response(SOSS_RESPONSE_ERROR, 
			"SQL Exception: " . $e->getMessage() );
	}
}

function delete_student() {
	try {
		$db = SOSS_DB::getInstance();
		
		$uname = soss_get_request('uname');
		
		$sql = "DELETE FROM %s WHERE student_class_id='%s' ";
		$sql .= "AND assignment_class_id='%s' ";
		$sql .= "AND student_username='%s'";
		
		$sql = sprintf( $sql, SOSS_DB::$FILES_TABLE,
			$db->dbclean( $_SESSION['classid'] ),
			$db->dbclean( $_SESSION['classid'] ),
			$db->dbclean( $uname ) );
		
		$result = $db->query($sql);
		$files = mysql_affected_rows();
		
		$sql = "DELETE FROM %s WHERE class_id='%s' ";
		$sql .= " AND username='%s'";
		$sql = sprintf( $sql, SOSS_DB::$STUDENT_TABLE,
			$db->dbclean($_SESSION['classid'] ), 
			$db->dbclean( $uname ) );
		$result = $db->query($sql);
		$students = mysql_affected_rows();
		
		$message = "Deleted $students student and $files file entries.";
		if( $students > 0 ) {
			$message .= "<br />It is now safe to manually delete all files in the repository";
			$message .= " that are associated with user \"{$uname}\" in class ID: \"{$_SESSION['classid']}\".";
		}
		
		soss_send_json_response(SOSS_RESPONSE_SUCCESS, $message);
		
	} catch( SOSS_DB_Exception $e ) {
		soss_send_json_response(SOSS_RESPONSE_ERROR, 
			"SQL Exception: " . $e->getMessage() );
	}
}

function delete_class() {
	
	try {
		$db = SOSS_DB::getInstance();
		
		$classid = soss_get_request('id');
		
		// Delete files
		$sql = "DELETE FROM %s WHERE student_class_id='%s' ";
		$sql .= "AND assignment_class_id='%s'";
		$sql = sprintf( $sql,
			SOSS_DB::$FILES_TABLE,
			$db->dbclean( $classid ),
			$db->dbclean( $classid ) );
		$result = $db->query($sql);
		$files = mysql_affected_rows();
	
		// Delete assignments
		$sql = "DELETE FROM %s WHERE class_id='%s'";
		$sql = sprintf( $sql, SOSS_DB::$ASSIGNMENTS_TABLE, $db->dbclean($classid) );
		$result = $db->query($sql);
		$assignments = mysql_affected_rows();
		
		// Delete students
		$sql = "DELETE FROM %s WHERE class_id='%s'";
		$sql = sprintf( $sql, SOSS_DB::$STUDENT_TABLE, $db->dbclean($classid) );
		$result = $db->query($sql);
		$students = mysql_affected_rows();
		
		// Delete classes
		$sql = "DELETE FROM %s WHERE class_id='%s'";
		$sql = sprintf( $sql, SOSS_DB::$CLASS_TABLE, $db->dbclean($classid) );
		$result = $db->query($sql);
		$classes = mysql_affected_rows();
	
		// If we've deleted the current class, make sure to remove it from
		// the session variables.
		if( $_SESSION['classid'] == $classid ) {
			$_SESSION['classid'] = -1;
			$_SESSION['class_name'] = "None";
		}
	
		$message = "Deleted $students students, $assignments assignments, and $files file entries.";
		$message .= "<br />It is now safe to manually delete all files in the repository";
		$message .= " under the directory named \"{$classid}\".";
	
		soss_send_json_response(SOSS_RESPONSE_SUCCESS, $message );
		
	}  catch( SOSS_DB_Exception $e ) {
		soss_send_json_response(SOSS_RESPONSE_ERROR, 
			"SQL Exception: " . $e->getMessage() );
	}
}